RE: Z axis trouble but only when printing
I solve myself this problem.The Z guide on the printing plate which is in the rear (two in front, one back)was not mounted in the right position (inverted, upside down).Best regards,
RE: Z axis trouble but only when printing
@Abel (and others): From my perspective, it appears that the root cause is an electrical noise/interference problem, whereby the activity of the relatively high power PWM of the nozzle heater interferes with the relatively weak analog signal from the load cell. It also appears that this noise/interference contributes to difficulty in X/Y homing (the "corner humping" problem where the print head repeatedly bangs against the front right corner of the chassis). Some CORE One units (like mine) are much more prone to this issue. I read that the firmware has been modified to filter the noisy signal, in an attempt to mitigate the problem - unfortunately that doesn't fix the issue for my CORE One. I also read here that Prusa support has sent a modified cable to at least one user with positive outcome.
Since I found the G-Code hack that disables the nozzle heater while the Nextruder is homing & cleaning the nozzle tip, I haven't had any difficulty getting my CORE One to print, and I haven't had the desire to investigate further. The post was by @david.b36 on May 17 and is found near the top of Page 2 of this thread in the English Forum. The two added lines are "M104 S0" and are marked by a comment that says "turn off temperature ADDED BY ME" (FORUM LINK: https://forum.prusa3d.com/forum/postid/750274/)
As a retired electrical engineer, I suspect the "true" fix for this problem is a hardware change, but I know that isn't economically feasible given the number of units in the field and the cost of such a modification. Furthermore, the G-Code hack is free and works well, at least for me. I am surprised, however, that this issue did not occur on previous printers with the Nextruder/loadcell/Love board, and therefore get fixed for CORE One. Perhaps there is a minor difference in how the Nextruder or Love board are connected/grounded to the gantry or xBuddy board, specifically in the CORE One, that exacerbates the issue? My desire to investigate further is low. It would be much easier to help out if the designs were fully open source (i.e. schematics/gerbers for the PCBs), but for understandable reasons Prusa now have to keep some aspects of their printer designs private.
RE: Z axis trouble but only when printing
I realize this is an older thread but it describes the exact problem I am having with my new fully assembled Core 1 printer I just received. It printed great for a couple days then I have not been able to get a print started. I went through all the troubleshooting steps listed on their webpage and after following everything they said to check I still can not get passed the errors; Printer collision has been detected and Filament failed to load. I finally decided to chat with tech support and went through all their checks including sending them pictures they had requested of various parts and they said everything look good. Support had me do a hard reset and re-flash the firmware and then calibrate the printer, still the same problem. They are sending me a new heat sink and bundle cable to see if that will fix the problem.
RE: Z axis trouble but only when printing
Not sure if anyone else has posted this but outside of adding the gcode I have had some luck with lowering the idle temperature down to around 120c in the filament settings. After reading through how as others have said the issue seems to be related to the heating being on and interfering with the load cell, turning down the idle temp seems to have reduced the noise enough to get some good readings. Ambient is 80F where I am so you might need to lower it further based on chamber temp.
RE: Z axis trouble but only when printing
I spent 5h yesterday on various chats with Prusa Support as I'm also having this issue and had reached the end of the troubleshooting page for the load cell. One rep (Kaloyan) confirmed that my load cell looked fine (despite being covered in gray material instead of white) and had me try downgrading to firmware 6.3.0 (my kit came with at least 6.3.2) which required a hard reset, reconnecting to the network, and redoing all the calibrations which passed. Didn't help. Then their shift ended and tried to pass me on to someone else but the connection dropped. Eventually resumed with another tech (Daniel) who is sending a replacement heatsink/load-cell and a thermistor. (I thought he meant the nozzle thermistor, but maybe the heat sink? (The nozzle was still hot when he had me check with the multimeter so the thermistor resistance was very low, around 30kΩ and rising. But it later got up to 100Ω.) I am suspicious that I'll have to rebuild the Nextruder twice or three times to eventually replace the main cable and/or LoveBoard too.
Starting to feel like I'm getting too old and life is too short to spend this much time tinkering with what really ought to be a pretty mature tech these days. Probably not a coincidence, considering my recent search terms, I saw an ad that Bambu is having a flash sale Tuesday (? check their store page for the countdown) where the base X1C is only US$799. (That's the model that is most similar to the CORE One.) Getting tempting to take advantage of China's anticompetitive subsidies.
RE: Z axis trouble but only when printing
After my conversation with tech support they sent me the Heatsink/ Loadcell and the main cable. I replaced the Heatsink / Loadcell first and it did not fix the problem. I then replaced the main cable they sent me and this did fix the problem. It has been printing fine ever since.
RE: Z axis trouble but only when printing
After replacing the cable it worked perfectly before I replaced it tho i could only get it to work with a modded gcode
RE: Z axis trouble but only when printing
I received a replacement heatsink (and thermistor) yesterday and replaced them today. No change... Z axis still misbehaving with the hot end on; still fine with it off. Probably a firmware update to briefly turn off the hot end heater while reading the loadcell would work. Will also try tweaking G-code.
RE: Z axis trouble but only when printing
You need to replace the cable. Mine looked perfect but was still the issue.
RE: Z axis trouble but only when printing
You need to replace the cable. Mine looked perfect but was still the issue.
Yeah, I tried to suggest that to the Prusa Tech, but they weren't interested. Now with the end of the de minimis exemption and carriers refusing shipments to USA, I figure I should let things settle down lest I get charged US$80 tariff (minimum flat rate if the shipper/carrier doesn't do things right) for a $30 cable. Can't find it on printed solid or I'd just buy one myself.
On the plus side, I was able to tweak the starter g-code with some additions that wait for the nozzle to get up to temperature and then turn it off again just before any probing (and also turn it off for homing) -- that seems to be working for me. Just a couple improvements to confirm with that that the next time I need to print something and I'll try to remember to post it here.
RE: Z axis trouble but only when printing
Ya i had read this before i talked with support and once i mentioned this fourm post they said ok well send you one out and ya i could only get mine to work by modding the gcode but once i replaced the cable it worked perfectly